Biodegradable shotgun wad system

ABSTRACT

Herein we describe embodiments of shotgun shells, methods for loading such shotgun shells, and methods for using them. In some embodiments, the shotgun shells utilize a multi-component wad system with a biodegradable powder wad that stays intact through the firing process, and a separate and chemically distinct biodegradable shot wad that breaks apart within one meter after being shot out of the barrel of a shotgun. A clean release of the shot can be obtained, providing both high performance and biodegradability. The biodegradable shot wad can be a biodegradable polyester.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 15/926,523, filed Mar. 20, 2018, which claims priority under 35U.S.C. § 119(e) to (i) U.S. Provisional Patent Application No.62/474,152, filed Mar. 21, 2017, and (ii) U.S. Provisional PatentApplication No. 62/474,157, filed Mar. 21, 2017. The entire disclosureof each of these applications is incorporated by reference herein.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable

BACKGROUND Field

The field relates to biodegradable wads associated with shotgun shellsoften used in and around aquatic environments.

Description of the Related Art

Shotguns are one of the most widely produced firearms worldwide. Forexample, the number of new shotguns manufactured in the United Stateswas close to one million in 2011. Moreover, the annual production ofshotgun shells is in the billions. Almost every shotgun shell that isfired discharges a wad (i.e., a “spent” wad) at a substantial distancefrom the sportsman. This distance prevents facile recovery, and thespent wad subsequently becomes pollution. Typically, and especially whenlead shot is not used, the wad is composed of plastic that does notbiodegrade, meaning the pollution is persistent in the environment.

The wads have multiple purposes in shotgun ammunition: (1) they separatethe powder from the shot; (2) they expand to form a gas seal thatretains the gas blast behind the shot as it travels down the barrel,efficiently maintaining velocity; (3) they provide protection to thebarrel (particularly important when non-lead shot is used); (4) they canprovide a cushioning effect to soften recoil; and (5) they can provideimproved shot patterns and minimize distortion of the shot.

The effect of non-biodegradable plastic debris is significant. Abandonedshotgun wads can present safety, nuisance, and environmental problems onland and in freshwater, estuarine, and marine waters. When a waterfowlhunter fires a shotgun armed with a shell containing a non-biodegradableplastic wad, the wad is shot out of the gun and often flies into theadjoining water. The quantity of abandoned shotgun wads in the nation'swaters is unknown; however, a shotgun wad is discharged with every shotfired, and many are abandoned. Target shooters (e.g., skeet, trap) oftenfire many shots in rapid succession, leaving a slew of plastic wads. Dueto the range of shotguns and the locations in which they are fired,there is often no easy way for sportsmen to recover each spent shotgunwad.

Abandoned wads enter the food chain as non-biodegradable plastic debris.Plastic wads are reported as one of the most common debris itemscollected during beach cleanups (NOAA. 2012. Guidebook to communitybeach cleanups). The buoyancy of many plastics causes the debris tofloat; therefore, plastic wads that do not wash ashore tend to float onthe water's surface. The floating wads can be mistaken for food bywaterfowl and other marine species. For example, wads have been found inthe stomach contents of ocean-foraging birds including the albatross(The Conservation Report. 2009). The consumption of plastic can lead toreduced fitness of aquatic species.

Abandoned wads also damage sensitive habitats. Over time, non-degradableplastic wads can break apart, causing massive amounts of non-degradablemicroplastics to enter the aquatic ecosystem. Currents can deposit thefloating wads on distant river banks and coasts, thereby impacting allmarine habitats, even habitats where hunting is prohibited. Furthermore,non-degradable plastic components can remain largely intact even afterspending years afloat, before fracturing into smaller microplastics. Themicroplastics can adsorb organic toxins, and do not readily break downinto compounds that can be assimilated into the natural carbon cycle.

Due in part to their low cost and versatility, production of plastics islikely to continue to increase. Worldwide commodity plastic productionhas increased by roughly 9% annually since 1950, with over 300 milliontons produced annually in 2016. Approximately 60% of all the plasticever made is accumulating in landfills and the natural environment(Geyer, R, et al., “Production, use, and fate of all plastics evermade”, Science Advances, 19 Jul. 2017, Vol. 3 (7): e1700782). It islikely that the increase in plastic production mirrors the increase inaquatic debris. Additionally, around half the global population resideswithin 100 kilometers of a coastline. With coastal populationsincreasing, the amount of aquatic and land-based plastic debris islikely to rise.

SUMMARY

The present disclosure relates to shotgun wads, and methods for theiruse, utilizing a wad system comprising at least two distinct andseparate wads, both of which comprise one or more biodegradablepolymers, wherein one of the two distinct wads comprises a powder wadthat is tough and stays intact throughout the firing process and flight,and the second of the two distinct wads comprises a shot wad that isrelatively brittle and breaks into multiple fragmented and independentpieces upon exiting the barrel after a shot. In some embodiments, theshot wad breaks apart within one meter of exiting the barrel.

The shot wad contains the shot and provides a barrier between the shotand the hull. It can take the form of a shot cup, a shot pipe wad, orany other shot wad.

The powder wad (also referred to as a gas seal or gas sealing wad orover-powder wad) separates the shot from the powder, and provides a gassealing component. The quality of the gas sealing capability can varybased on the formulation and shape of the powder wad. The powder wad andthe shot wad can each comprise one or more biodegradable polymers, andthe biodegradable polymers can be the same polymer or a differentpolymer.

Additional wads can be used, including but not limited to one or more ofa cushion wad, spacer wad, and overshot wad.

Particular advantages of this wad system in a shotgun shell can include,but are not limited to advantages related to the biodegradable powderwad: (i) by staying intact, the powder wad can perform the gas sealingfunction of gas seals of commercially available ammunition; (ii) bystaying intact, the powder wad can perform as well as, and in somecases, better than commercial ammunition; and (iii) by staying intactduring flight but eventually fragmenting or eroding during degradation,the powder wad can adhere to one or more standards for biodegradablewithout impacting performance.

Particular advantages of this wad system in a shotgun shell can include,but are not limited to advantages related to the biodegradable shot wad:(i) by breaking apart into multiple pieces, the biodegradable shot wadis less visually unappealing when abandoned in the environment, as it isless obvious to the naked eye; (ii) by breaking apart into multiplepieces, increased surface area of the biodegradable shot wad is exposed,which tends to increase the rate of biodegradation; (iii) by breakingapart into multiple pieces, the biodegradable shot wad can be lesslikely to cause injuries if ingested by an animal; and (iv) by breakingapart into multiple pieces, the biodegradable shot wad provides acleaner release of the shot than typical prior art plastic wads, all thewhile the powder wad stays intact and efficiently contains the expandinggases to propel the shot.

In some embodiments, the biodegradable shot wad utilizes a “shot pipe”wad design with two open ends. The biodegradable shot pipe wad, byvirtue of not having a base, allows slightly more room in the crowdedhull for additional powder or shot. This is particularly advantageouswhen used in conjunction with steel shot, which is not as dense as lead.Hunters typically use larger shot when hunting with steel relative tolead, meaning space is at a premium in the load. In some embodiments,the biodegradable shot wad utilizes a cup design in which at least oneend is enclosed or partially enclosed. The design can include one openend.

In some embodiments, the shot wad is neither a shot pipe wad or a shotcup wad. For example, a modified shot pipe wad could be used in whichone end contains a thin strip of plastic that can direct thefragmentation pattern when the shot wad breaks apart, which caninfluence the shot pattern.

In some embodiments, the key is the use of a tough biodegradable polymerformulation for the powder wad such that the powder wad stays intactduring firing, flight and/or landing, and the use of a somewhat brittlebiodegradable polymer formulation in the shot wad such that the shot wadbreaks apart shortly after firing when fired at typical operating speedand pressure (e.g., between 8,000 psi and 11,500 psi for 12 gauge, 341ammunition for shotgun ammunition). The shot wad may begin to fracturewhile still within the barrel, but it does not break apart until leavingthe barrel. Instead, the shot wad breaks apart within a short distanceof leaving the barrel. In some embodiments, the shot wad breaks apartwithin one meter of leaving the barrel, but other distances arecontemplated, e.g., within 1 foot, within 2 feet, within 3 feet, within10 feet, within 20 feet, etc. As used herein, “break apart” means a wadfragments such that pieces are displaced in a manner wherein previouslycontiguous pieces become physically separated. In some embodiments, theshot wad of the present invention can have fracture lines similar tothose in an intact puzzle while the shot wad is still inside the barrel,during which time the shot wad remains functionally intact, and thebarrel remains protected from the shot, until the shot wad leaves thebarrel, when the shot wad breaks apart.

The brittle plastic formulations utilized in the shot wad would not beacceptable for molding into and use as a powder wad, as the resultingpowder wad would likely fragment and thus not perform the requisite gassealing function very well. In some embodiments, the shot wad and thepowder wad utilize different biodegradable polymers. In someembodiments, the powder wad comprises a biodegradable polymer designedto stay intact during firing due, in part to, its material properties.In some embodiments, the selection of the biodegradable polymer and thedesign of the powder wad facilitate the powder wad staying intact. Insome embodiments, the shot wad comprises a biodegradable polymerdesigned to fragment after firing due, in part to, its materialproperties. In some embodiments, the selection of the biodegradablepolymer and the design of the shot wad facilitate fragmentation.

It is noted that when the biodegradable shot wad is combined with aproperly functioning powder wad, the biodegradable shot wad experiencesless impact force upon firing than does the powder wad, as well as adifferent relative directional component of that force, and thus canstay functionally intact until exiting the gun.

Analogously, when utilizing shot wad designs that lack pre-slit sections(petals) designed to fold back, the tough formulations used for thepowder wad would provide worse targeting performance if those same toughformulations were used to produce the shot wad. If the shot wads usedherein did not break apart soon after leaving the barrel, then shotpatterns would be adversely impacted. For this reason, conventionallyformulated plastic shotgun wads which remain intact after firing do nothave the advantages described herein. The shot wads described hereingenerally lack petals that bend back to release shot, although suchdesigns with petals are contemplated.

The biodegradable shot wads described herein break apart shortly afterleaving the barrel. In some embodiments, the biodegradable shot wadsbreak apart within one meter of leaving the barrel, but other metrics ofdistance are contemplated. In some embodiments, the biodegradable shotwads fragment when shot at an initial velocity exiting the barrel at1,000 feet per second. It is noted that the shot wad and the averageshot pellet are traveling at approximately the same speed upon firstexiting the barrel. The distance at which the biodegradable shot wadsbreak apart after leaving the barrel, and the pattern of the break orfragment, can be controlled, at least in part, by the design of the shotwad and the biodegradable polymer formulation that is utilized.

When the biodegradable shot wad breaks apart after leaving the barrel,the shot pellets are gently released from the clutches of the shot wadand continue towards the target. Conventional shot cup wads reproduciblyrelease shot, but the shot can be subjected to small additional forcesthat result in a less clean release of the shot, and inferior patternsrelative to the biodegradable wad system described herein.

The biodegradable powder wads used herein can include any biodegradablepolymer material that can withstand the impact force of firing andperform the functions of a powder wad including the gas sealingfunction. For example, formulations of biodegradable polymers comprisinga polyhydroxyalkanoate polymer (PHA), polybutylene succinate (PBS),poly(butylene succinate-co-adipate) (PBSA), a polybutylene succinatecopolymer other than PBSA (PBS(c)), and combinations thereof, canperform this function. Other biodegradable polymers, includingpolylactic acid (PLA) and polycaprolactone (PCL), can also be used,especially if used in combination with other polymers. Other polymers,including oxo-biodegradable polyethylene and other polymer compositions,can also be used. In some embodiments, biodegradability can be definedaccording to compliance with international standards. Other non-plasticbiodegradable polymers can also be used as the powder wad, includingcork, fiber, wool felt, and cellulosic products such as paperboard. Ingeneral, these materials do not provide as good gas sealing propertiesas some of the plastic-based powder wads, but notwithstanding the slightinefficiency, they can perform adequately depending on a variety offactors. Coating such materials with a wax composition, for examplebeeswax, can improve performance.

The powder wad described herein comprises any biodegradable polymerdescribed herein. The powder wad can comply with one or more definitionsof biodegradable. The ASTM D6400 is entitled Standard Specification forLabeling of Plastics Designed to be Aerobically Composted in Municipalor Industrial Facilities. See ASTM Standard D6400, 2004, “StandardSpecification for Compostable Plastics,” ASTM International, WestConshohocken, Pa., 2004, DOI: 10.1520/D6400-04, www.astm.org, whereinthe ASTM Standard D6400, 2004 is incorporated by reference in itsentirety. The ASTM D6400 identifies three governing provisions that mustbe met: the product must physically degrade such that the product is not“readily distinguishable” from the surrounding compost, the product mustbe consumed by microorganisms at a rate comparable to other knowncompostable materials, and the product cannot adversely impact theability of the compost to support plants. This specification coversplastics and products made from plastics that are designed to becomposted in municipal and industrial aerobic composting facilities.

In some embodiments, a material is biodegradable if it undergoesdegradation by biological processes during composting to yield CO₂,water, inorganic compounds, and biomass at a rate consistent with otherknown compostable materials. In some embodiments, a material isbiodegradable if it leaves no visible, distinguishable, or toxicresidue. Bioplastics can be defined by where the material comes from orits origin. Bioplastics can be plant-derived such as from corn, sugar,or starch, compared to traditional plastics that are typicallypetroleum-based. Bioplastics can be defined by a time frame ofdegradation, wherein bioplastics degrade significantly faster than therate of traditional plastics. Biodegradation can be defined by a changeof material or degradation by naturally occurring microorganisms over aperiod of time. Degradation can be defined by a deleterious change inthe chemical structure, physical properties, or appearance of thematerial. See ASTM D6400, 2004. A biodegradable material can be definedby the ability to completely break down and return to nature, i.e.,decompose into elements found in nature within a reasonably short periodof time such as one year after customary disposal. A biodegradablematerial can be defined as a material wherein all the organic carbon canbe converted into biomass, water, carbon dioxide, and/or methane via theaction of naturally occurring microorganisms such as bacteria and fungi,in timeframes consistent with the ambient conditions of the disposalmethod. See ASTM D883. The powder wad can be described as bio-based,biodegradable, or compostable.

The powder wad described herein can comprise PBSA, and can comprise byweight at least 10% PBSA, at least 20%, at least 30%, at least 40%, atleast 50%, at least 60%, at least 70%, at least 80%, at least 90%, or atleast 95% PBSA, or ranges incorporating any of the foregoing values. Inembodiments in which the powder wad comprises PBSA, it is preferablewhen the gas seal wad comprises at least 60% by weight PBSA. In someembodiments, other biodegradable polymers are also incorporated into theshotgun gas seal wads. For example, PHA can be included.

The powder wad described herein can comprise PBS, and can comprise byweight at least 10% PBS, at least 20%, at least 30%, at least 40%, atleast 50%, at least 60%, at least 70%, at least 80%, at least 90%, or atleast 95% PBS, or ranges incorporating any of the foregoing values. Inpreferred embodiments in which the powder wad comprises PBS, it ispreferable when the powder wad comprises at least 60% by weight PBS. Insome embodiments, other biodegradable polymers are also incorporatedinto the shotgun gas seal wads. For example, PHA can be included.

The powder wad described herein can comprise PBS(c), and can comprise byweight at least 10% PBS(c), at least 20%, at least 30%, at least 40%, atleast 50%, at least 60%, at least 70%, at least 80%, at least 90%, or atleast 95% PBS(c), or ranges incorporating any of the foregoing values.In preferred embodiments in which the powder wad comprises PBS(c), it ispreferable when the powder wad comprises at least 60% by weight PBS(c).In some embodiments, other biodegradable polymers are also incorporatedinto the shotgun gas seal wads. For example, PHA can be included.

The powder wad described herein can comprise PLA, and can comprise byweight at least 10% PLA, at least 20%, at least 30%, at least 40%, atleast 50%, at least 60%, at least 70%, at least 80%, at least 90%, or atleast 95% PLA, or ranges incorporating any of the foregoing values. Insome embodiments, other biodegradable polymers are also incorporatedinto the shotgun gas seal wads. For example, PHA can be included.

The powder wad described herein can comprise PCL, and can comprise byweight at least 10% PCL, at least 20%, at least 30%, at least 40%, atleast 50%, at least 60%, at least 70%, at least 80%, at least 90%, or atleast 95% PCL, or ranges incorporating any of the foregoing values. Insome embodiments, other biodegradable polymers are also incorporatedinto the shotgun gas seal wads. For example, PHA can be included.

Blends of certain biodegradable polymers with a relatively small amount(0.1-25%) of PHA may be beneficial in facilitating the rate ofbiodegradation in marine environments relative to powder wads thatcontain no PHA. In some embodiments of such blends, the weight fractionof the first biodegradable polymer, such as PBSA, PBS, and PBS(c), as apercentage of the total biodegradable polymer composition is greaterthan about 50% (e.g., greater than 60%, greater than 70%, greater than80%, greater than 90%, or ranges incorporating any of the foregoingvalues). In some embodiments, the weight ratio of PBSA, PBS, PBS(c) toPHA is greater than 4:1 (e.g., greater than 5:1, greater than 6:1,greater than 7:1, greater than 8:1, greater than 9:1, greater than 10:1,greater than 11:1, greater than 12:1, greater than 13:1, greater than14:1, or greater than 15:1, or ranges incorporating any of the foregoingvalues). In some embodiments, the processability of blends with higherconcentrations of PHA tends to be poor, and additives that enhance theprocessability of said blends can increase persistence or toxicity ofthe resulting wads in the environment.

The powder wad described herein can comprise PHA, and can comprise byweight at least 10% PHA, at least 20%, at least 30%, at least 40%, atleast 50%, at least 60%, at least 70%, at least 80%, at least 90%, or atleast 95% PHA. In some embodiments, more than one different type of PHAis used. In some embodiments, other biodegradable polymers are alsoincorporated into the shotgun gas seal wads.

In contrast, the biodegradable shot wad described herein comprises abiodegradable formulation that is designed to fragment. In someembodiments, the biodegradable shot wad is not tough enough to withstandthe forces of the firing process. Suitable compositions comprise one orbiodegradable plastics, and preferably comprise a biodegradablepolyester. In some embodiments, suitable compositions comprise one ormore biodegradable polyesters selected from the group consisting of PHA,PBS, PBSA, PCL, PLA, and combinations thereof. Preferably, thebiodegradable plastic formulation used to make the shot wad has aspecific gravity greater than 1.0, and more preferably, greater than1.1, such that wad fragments that enter aquatic environments will tendto sink. Certain biodegradable polymers have a specific gravity greaterthan 1.0, causing its tendency to sink. In some embodiments, thebiodegradable polymer of the shot wad has a specific gravity greaterthan the ambient aquatic environment. The specific gravity of one ormore wads of the wad system in g/cm3 can be greater than water, greaterthan one, greater than saltwater, greater than 1.025, greater than 1.1,greater than 1.2, greater than 1.3, greater than 1.4, between 1 and1.45, or between 1.2 and 1.45, or ranges incorporating any of theforegoing values.

The shot wad described herein can comprise PBSA, and can comprise byweight at least 10% PBSA, at least 20%, at least 30%, at least 40%, atleast 50%, at least 60%, at least 70%, at least 80%, at least 90%, or atleast 95% PBSA, or ranges incorporating any of the foregoing values. Insome embodiments, other biodegradable polymers are also incorporatedinto the shot wad. For example, PHA can be included.

The shot wad described herein can comprise PBS, and can comprise byweight at least 10% PBS, at least 20%, at least 30%, at least 40%, atleast 50%, at least 60%, at least 70%, at least 80%, at least 90%, or atleast 95% PBS, or ranges incorporating any of the foregoing values. Insome embodiments, other biodegradable polymers are also incorporatedinto the shot wad. For example, PHA can be included.

The shot wad described herein can comprise PBS(c), and can comprise byweight at least 10% PBS(c), at least 20%, at least 30%, at least 40%, atleast 50%, at least 60%, at least 70%, at least 80%, at least 90%, or atleast 95% PBS(c), or ranges incorporating any of the foregoing values.In some embodiments, other biodegradable polymers are also incorporatedinto the shot wad. For example, PHA can be included.

The shot wad described herein can comprise PLA, and can comprise byweight at least 10% PLA, at least 20%, at least 30%, at least 40%, atleast 50%, at least 60%, at least 70%, at least 80%, at least 90%, or atleast 95% PLA, or ranges incorporating any of the foregoing values. Insome embodiments, other biodegradable polymers are also incorporatedinto the shot wad. For example, PHA can be included.

The shot wad described herein can comprise PCL, and can comprise byweight at least 10% PCL, at least 20%, at least 30%, at least 40%, atleast 50%, at least 60%, at least 70%, at least 80%, at least 90%, or atleast 95% PCL, or ranges incorporating any of the foregoing values. Insome embodiments, other biodegradable polymers are also incorporatedinto the shot wad. For example, PHA can be included.

The shot wad described herein can comprise PHA, and can comprise byweight at least 10% PHA, at least 20%, at least 30%, at least 40%, atleast 50%, at least 60%, at least 70%, at least 80%, at least 90%, or atleast 95% PHA, or ranges incorporating any of the foregoing values. Insome embodiments, other biodegradable polymers are also incorporatedinto the shot wad.

In addition to one or more biodegradable polymers, the powder wad andthe shot wad can comprise additives, including lubricants, mold releaseagents, impact modifiers, pigments or other colorants, other polymericcomponents, photodegradation enhancers, stabilizers, plasticizers, andother plastic additives. Environmentally toxic plastic additives shouldbe avoided.

In preferred embodiments, the biodegradable wads biodegrade reasonablywell in most environments in which the wads might ultimately end up,including wastewater treatment facilities, soil, freshwaterenvironments, estuarine environments, and marine environments.

In some embodiments, a shotgun shell is provided. The shotgun shell caninclude a shotgun case having a boundary defining an enclosed space, apowder wad, and a biodegradable shot wad confined within the enclosedspace and having the properties described above. Additional componentsof the shotgun shell include the hull, primer, powder, shot, andsupplemental wads if needed.

In some embodiments, a method of shooting a shotgun shell is provided.The method can include the step of providing a shotgun case having aboundary defining an enclosed space, a biodegradable powder wadcomprising a biodegradable polymer, and a biodegradable shot wadcomprising a biodegradable plastic confined within the enclosed space.The method can include the step of inserting the shotgun shell into ashotgun. The method can include the step of firing the shotgun. The wadsexit the barrel of the shotgun upon firing. The method can include thestep of exposing the biodegradable shot wad and the biodegradable powderwad to a land or aquatic environment after having been fired from theshotgun.

In some embodiments, a method of loading a shotgun shell is provided.The method includes the steps of providing a primed shotshell hull,sequentially adding powder, a biodegradable powder wad, a biodegradableshot wad, and shot to said hull, and then crimping the loaded hull,wherein the biodegradable powder wad stays intact after firing, andwherein the biodegradable shot wad breaks apart after firing within onemeter of exiting the shotgun barrel at a velocity exceeding 1,000 feetper second.

In some embodiments, a shotgun shell is provided. The shotgun shell caninclude a shotgun case having a boundary defining an enclosed space. Theshotgun shell can include powder. The shotgun shell can include shot.The shotgun shell can include a biodegradable powder wad configured tobe confined within said boundary. The shotgun shell can include abiodegradable shot wad configured to be confined within said boundary.In some embodiments, said biodegradable shot wad at least partiallysurrounds said shot in the shotgun case. In some embodiments, saidbiodegradable shot wad comprises a biodegradable material. In someembodiments, said biodegradable powder wad physically separates saidpowder from said shot. In some embodiments, said biodegradable powderwad comprises a biodegradable material. In some embodiments, saidbiodegradable powder wad is physically and chemically distinct from saidbiodegradable shot wad. In some embodiments, upon firing of said shotgunshell from a shotgun having a barrel, said biodegradable powder wad isconfigured to stay intact during flight and landing and saidbiodegradable shot wad is configured to break apart into multiplediscrete pieces during flight or landing.

In some embodiments, said biodegradable powder wad comprises abiodegradable polymer that satisfies the ASTM D6400 standard (2004). Insome embodiments, said biodegradable shot wad comprises a biodegradablepolyester. In some embodiments, said biodegradable powder wad comprisesa biodegradable polyester. In some embodiments, upon firing of saidshotgun shell from a shotgun having a barrel such that said shot exitssaid barrel at a velocity exceeding 1,000 feet per second, saidbiodegradable powder wad stays intact and does not break apart withinone meter of exit from said barrel. In some embodiments, upon firing ofsaid shotgun shell from a shotgun having a barrel such that said shotexits said barrel at a velocity exceeding 1,000 feet per second, saidbiodegradable shot wad breaks apart into multiple discrete pieces withinone meter of exit from said barrel. In some embodiments, saidbiodegradable powder wad comprises a biodegradable polymer selected fromthe group consisting of PHA, PLA, PCL, PBS, PBSA, and PBS(c). In someembodiments, said biodegradable powder wad comprises a biodegradablematerial selected from the group consisting of wool felt, cork, fiber,and paperboard. In some embodiments, said biodegradable powder wadcomprises oxo-biodegradable polyethylene. In some embodiments, saidbiodegradable shot wad comprises a biodegradable polymer selected fromthe group consisting of PHA, PLA, PCL, PBS, and PBSA. In someembodiments, said biodegradable shot wad comprises PHA. In someembodiments, said biodegradable shot wad has a specific gravity greaterthan 1.1. In some embodiments, said biodegradable shot wad is abiodegradable shot pipe wad comprising a generally cylindrical wad thathas two open ends. In some embodiments, said biodegradable shot wad is acup-style wad with one open end and one closed end, wherein said oneclosed end is positioned adjacent to the powder wad. In someembodiments, said shotgun shell provides superior shot patterning whenfired than occurs in an otherwise identical shell wherein the chemicalcomposition of the biodegradable shot wad is the same as thebiodegradable powder wad.

In some embodiments, a method of shooting a shotgun shell is provided.The method can include providing a shotgun shell having a boundarydefining an enclosed space and powder, shot, a biodegradable powder wad,and a biodegradable shot wad confined within said enclosed space. Insome embodiments, said biodegradable shot wad surrounds said shot withinsaid enclosed space within said shotgun shell. In some embodiments, saidbiodegradable powder wad physically separates said powder from saidshot. The method can include providing a shotgun having a barrel. Themethod can include loading said shotgun shell into said shotgun. Themethod can include firing the shotgun, whereby the shot, thebiodegradable powder wad and the biodegradable shot wad are launched outof said barrel to expose said biodegradable shot wad and saidbiodegradable powder wad to a terrestrial or aquatic environment. Insome embodiments, said biodegradable wads biodegrade. In someembodiments, said biodegradable shot wad comprises a biodegradablematerial. In some embodiments, said biodegradable powder wad comprises abiodegradable material. In some embodiments, said biodegradable powderwad is physically and chemically distinct from said biodegradable shotwad. In some embodiments, upon firing of said shotgun shell from theshotgun, said biodegradable powder wad stays intact and does not breakapart during flight or landing, and said biodegradable shot wad breaksapart into multiple discrete pieces during flight or landing.

In some embodiments, said biodegradable powder wad comprises abiodegradable polymer that satisfies the ASTM D6400 standard (2004). Insome embodiments, said biodegradable shot wad comprises a biodegradablepolyester. In some embodiments, said biodegradable powder wad comprisesa biodegradable polyester. In some embodiments, upon firing of saidshotgun shell from a shotgun having a barrel such that said shot exitssaid barrel at a velocity exceeding 1,000 feet per second, saidbiodegradable powder wad stays intact and does not break apart withinone meter of exit from said barrel. In some embodiments, upon firing ofsaid shotgun shell from a shotgun having a barrel such that said shotexits said barrel at a velocity exceeding 1,000 feet per second, saidbiodegradable shot wad breaks apart into multiple discrete pieces withinone meter of exit from said barrel. In some embodiments, saidbiodegradable powder wad comprises a biodegradable polymer selected fromthe group consisting of PHA, PLA, PCL, PBS, PBSA, and PBS(c). In someembodiments, said biodegradable powder wad comprises a biodegradablematerial selected from the group consisting of wool felt, cork, fiber,and paperboard. In some embodiments, said biodegradable powder wadcomprises oxo-biodegradable polyethylene. In some embodiments, saidbiodegradable shot wad comprises a biodegradable polymer selected fromthe group consisting of PHA, PLA, PCL, PBS, and PBSA. In someembodiments, said biodegradable shot wad comprises PHA. In someembodiments, said biodegradable shot wad has a specific gravity greaterthan 1.1. In some embodiments, said biodegradable shot wad is abiodegradable shot pipe wad comprising a generally cylindrical wad thathas two open ends. In some embodiments, said biodegradable shot wad is acup-style wad with one open end and one closed end, wherein said oneclosed end is positioned adjacent to the powder wad within said shell.In some embodiments, said shotgun shell provides superior shotpatterning when fired than occurs in an otherwise identical shellwherein the chemical composition of the biodegradable shot wad is thesame as the biodegradable powder wad.

In some embodiments, a method of loading a shotgun shell is provided.The method can include providing a shotshell hull. The method caninclude providing powder. The method can include providing shot. Themethod can include providing a biodegradable powder wad. The method caninclude providing a biodegradable shot wad. The method can includeloading said powder, said biodegradable powder wad, said biodegradableshot wad, and said shot into said shotgun hull. The method can includecrimping said shotgun hull loaded with said powder, said biodegradablepowder wad, said biodegradable shot wad, and said shot. In someembodiments, said biodegradable shot wad comprises a biodegradablematerial. In some embodiments, said biodegradable powder wad comprises abiodegradable material. In some embodiments, said biodegradable powderwad is physically and chemically distinct from said biodegradable shotwad. In some embodiments, upon firing of said shotgun shell from ashotgun, said biodegradable powder wad stays intact and does not breakapart during firing or landing, and said biodegradable shot wad breaksapart into multiple discrete pieces during firing or landing.

In some embodiments, said biodegradable powder wad comprises abiodegradable polymer that satisfies the ASTM D6400 standard (2004). Insome embodiments, said biodegradable shot wad comprises a biodegradablepolyester. In some embodiments, said biodegradable powder wad comprisesa biodegradable polyester. In some embodiments, upon firing of saidshotgun shell from a shotgun having a barrel such that said shot exitssaid barrel at a velocity exceeding 1,000 feet per second, saidbiodegradable powder wad stays intact and does not break apart withinone meter of exit from said barrel. In some embodiments, upon firing ofsaid shotgun shell from a shotgun having a barrel such that said shotexits said barrel at a velocity exceeding 1,000 feet per second, saidbiodegradable shot wad breaks apart into multiple discrete pieces withinone meter of exit from said barrel. In some embodiments, saidbiodegradable powder wad comprises a biodegradable polymer selected fromthe group consisting of PHA, PLA, PCL, PBS, PBSA, and PBS(c). In someembodiments, said biodegradable powder wad comprises a biodegradablematerial selected from the group consisting of wool felt, cork, fiber,and paperboard. In some embodiments, said biodegradable powder wadcomprises oxo-biodegradable polyethylene. In some embodiments, saidbiodegradable shot wad comprises a biodegradable polymer selected fromthe group consisting of PHA, PLA, PCL, PBS, PBSA, and PBS(c). In someembodiments, said biodegradable shot wad comprises PHA. In someembodiments, said biodegradable shot wad has a specific gravity greaterthan 1.1. In some embodiments, said biodegradable shot wad is abiodegradable shot pipe wad comprising a generally cylindrical wad thathas two open ends. In some embodiments, said biodegradable shot wad is acup-style wad with one open end and one closed end, wherein said oneclosed end is positioned adjacent to the powder wad within said shell.In some embodiments, said shell provides superior shot patterning whenfired than occurs in an otherwise identical shell wherein the chemicalcomposition of the biodegradable shot wad is the same as thebiodegradable powder wad.

In some embodiments, a shotgun shell is provided. The shotgun shell caninclude a shotgun case having a boundary defining an enclosed space. Theshotgun shell can include a gas seal wad. The shotgun shell can includea biodegradable shot pipe wad confined within said enclosed space. Insome embodiments, said biodegradable shot pipe wad comprises a generallycylindrical wad which contains shot pellets in the shell and has twoopen ends. In some embodiments, said biodegradable shot pipe wadcomprises a biodegradable polymer.

In some embodiments, said biodegradable shot pipe wad comprises abiodegradable polyester. In some embodiments, said biodegradable shotpipe wad comprises a biodegradable polyester selected from the groupconsisting of a polyhydroxyalkanoate polymer, a polybutylene succinatepolymer, a polybutylene succinate adipate polymer, and a polylactic acidpolymer. In some embodiments, said shell is formulated such that uponbeing fired out of a shotgun, said biodegradable shot pipe wad leavesthe shotgun intact and then begins to fragment in the air prior tolanding. In some embodiments, said gas seal wad comprises abiodegradable polymer.

In some embodiments, a method of shooting a shotgun shell is provided.The method can include providing a shotgun case having a boundarydefining an enclosed space and a biodegradable shot pipe wad confinedwithin said enclosed space. In some embodiments, said biodegradable shotpipe wad is a cylindrical wad with two open ends and is situated aroundshot pellets. In some embodiments, said biodegradable shot pipe wadcomprises a biodegradable polymer. The method can include loading saidshotgun case into a shotgun. The method can include firing the shotgun,whereby the biodegradable shot pipe wad is discharged from the barrel ofthe gun. The method can include exposing said biodegradable shot pipewad to a terrestrial or aquatic environment, wherein said biodegradablewad biodegrades.

In some embodiments, said biodegradable shot pipe wad comprises abiodegradable polymer having a specific gravity greater than 1.1. Insome embodiments, said biodegradable shot pipe wad comprises abiodegradable starch polymer. In some embodiments, said biodegradableshot pipe wad comprises a biodegradable polyester. In some embodiments,said biodegradable shot pipe wad comprises a biodegradable polyesterselected from the group consisting of a polyhydroxyalkanoate polymer, apolybutylene succinate polymer, a polybutylene succinate adipatepolymer, and a polylactic acid polymer. In some embodiments, said shellis formulated such that upon being fired out of a shotgun, saidbiodegradable shot pipe wad leaves the shotgun intact and then begins tofragment in the air prior to landing. In some embodiments, said shotguncase having a boundary defining an enclosed space additionally comprisesa gas seal wad, wherein said gas seal wad comprises a biodegradablepolymer.

In some embodiments, a biodegradable shot pipe wad component comprisinga biodegradable polymer is provided. In some embodiments, saidbiodegradable shot pipe wad component is suitable for use in a shotgunshell. In some embodiments, said biodegradable wad is a shot wad thathaving a generally cylindrical shape with two open ends. In someembodiments, said biodegradable shot pipe wad has a specific gravitygreater than 1.1. In some embodiments, said biodegradable shot pipe wadcomprises a biodegradable polymer selected from the group consisting ofa starch polymer, a polyhydroxyalkanoate polymer, a polybutylenesuccinate polymer, a polybutylene succinate co-polymer, and a polylacticacid polymer. In some embodiments, said biodegradable shot pipe wad haslongitudinal grooves, wherein said grooves facilitate patterned crackingin a spent wad. In some embodiments, said biodegradable shot pipe wad isproduced using an extrusion molding process.

Some biodegradable wads are commercially available; in fact, all wadsused to be biodegradable. Until the invention of plastic wads, shotgunwads were made of cardboard, fiber, felt, cork, and other naturalproducts, examples of which are still available commercially. However,plastic wads have price and performance advantages, resulting in theirwidespread adoption.

Biodegradable plastic wads have been taught in the prior art but haveyet to make a substantial impact commercially. Chiesa (WO2015033081 A1)teaches a biodegradable plastic wad comprising a blend of a polyalkylenesuccinate, including polybutylene succinate, with a polyhydroxyalkanoatepolymer.

Havens et al. (U.S. Pat. No. 9,528,800) teach the use of apolyhydroxyalkanoate wad. Polyhydroxyalkanoate wads have excellentdegradability, but tend to be very brittle or, if made more rubbery, canbe very difficult to process. Havens teaches a wad comprisingpolyhydroxyalkanoate, and teaches the use of wads that stay intact whilewithin the barrel, but break apart soon after leaving the barrel.Unfortunately, Applicants have discovered, after extensive fieldtesting, that this is an extraordinarily delicate balance when the gassealing wad and shot wad are made from the same plastic formulation.Weather conditions, storage time, molding conditions, and many othervariables can impact the wad performance, making it very inconsistent.Sometimes the wad stays intact well after leaving the barrel, and otherwads break apart inside the barrel. Applicants believe that such a wadsystem as described by Havens can be improved, as described herein.

Shahid et al. (U.S. Pat. No. 5,859,090) teach the use ofpolycaprolactone shotgun wads. Polycaprolactone wads are problematic,among other reasons, because of the low melt temperature of the polymer.For example, if a polycaprolactone wad was left in a truck cab on a hotsunny day, shape changes in the wad could occur, which could compromiseperformance and potentially cause a misfire, which can be dangerous.

Hampton et al. (GB 2496180) teach a composite material which includes amajor percentage of natural-starch polyester polymer and a minorpercentage of powdered chemically-untreated straw. The straw providesuniform solidity to the finished composite material, thereby allowinguse of the composite in conventional extruding and injection molding.The straw is essential to the device of Hampton to improve dimensionalstability during molding of the material, and prevents or limitsshrinkage. Unlike Hampton, the PBSA wads do not rely on straw forstructural stability. In some embodiments, the wads do not include solidmaterial such as straw in the material. Rather, in some embodiments, thePBSA itself provides dimensional stability and uniform solidity of thefinished composite material.

Shotgun shells often utilize more than one wad in the shell, inparticular when heavier loads are used with larger shot. For example, agas sealing wad (also referred to as a powder wad, or gas seal) is oftencombined with a shot cup wad. Other common wads include overshot wads,filler wads, and cushion wads. As described above, many biodegradableplastics are brittle, and cannot perform wad functions such as gassealing or protecting the barrel from shot, as they fragment uponfiring.

Accordingly, there remains a need for a high-performance biodegradableshotgun wad. A modification to shotgun wads to mitigate the impact ofaquatic, plastic debris would be a viable and effective optionprovided: 1) the modified shotgun wad has performance characteristicscomparable to non-biodegradable plastic wads; 2) the wad degradesreasonably quickly once it is abandoned on land or in an aquaticenvironment, and, once degraded, is environmentally benign along withany additives; and 3) the wad is not too expensive to be of practicaluse. Due in part to the lack of a sufficiently viable alternative,government regulators fail to limit the enormous amount of plasticpollution created by sportsmen and sportswomen each year.

BRIEF DESCRIPTION OF THE DRAWINGS

The summary above, and the following detailed description, will bebetter understood in view of the drawings that depict details ofpreferred embodiments.

FIG. 1 shows a cutaway perspective view of a shotgun shell.

FIG. 2 shows one embodiment of a biodegradable shot pipe shotgun wadwhich can be combined with an independent shot wad in a shotgun shell.

FIG. 3 shows a cutaway perspective view of one embodiment of a shotgunshell loaded with a multi-component wad system comprising a first wadthat is a gas sealing wad and a second wad that is a shot cup wad.

FIGS. 4A and 4B show a photographic image of one embodiment of a PBSAgas seal wad. FIG. 4A is a photographic image showing the side andbottom of the gas seal; i.e., the end of the gas seal in direct contactwith the powder, while FIG. 4B is a photographic image showing the sideand the top end (i.e., the end closest to the shot) of the gas seal.

FIG. 5 shows a time series of photographic images taken with anEdgertronic high-speed camera at roughly 30,000 frames per second,showing images of a shotgun firing a shell loaded with a multi-componentwad system including a gas sealing wad comprising PBSA. The series ofimages shows the shot and wads leaving the shotgun barrel just after theweapon is fired.

FIG. 6 shows a time series of photographic images taken with anEdgertronic high-speed camera at roughly 30,000 frames per second,showing images of a shotgun firing a shell loaded with a multi-componentwad system including a gas sealing wad comprising PBSA. The series ofimages shows the shot and wads leaving the shotgun barrel just after theweapon is fired.

FIG. 7 shows a time series of photographic images taken with anEdgertronic high-speed camera at roughly 30,000 frames per second,showing images of a shotgun firing a shell loaded with a multi-componentwad system including a natural fiber powder wad. The series of imagesshows the shot and wads leaving the shotgun barrel just after the weaponis fired.

FIG. 8 is a photographic image taken with an Edgertronic high-speedcamera at 30,000 frames per second showing a shot wad emerging intactfrom the barrel.

FIG. 9 is a photographic image taken with an Edgertronic high-speedcamera at 30,000 frames per second showing a shot wad that emergedintact from the barrel, albeit with a clear split that increased in sizeas the wad's distance from the barrel increased.

FIG. 10 is a photographic image taken with an Edgertronic high-speedcamera at 30,000 frames per second showing a shot wad emerging intactfrom the barrel, albeit with multiple hairline splits apparent in theshot wad.

FIG. 11 is a photographic image showing fragments of three shot wadsthat were left together in a 250 micron mesh bag in a saltwaterenvironment for a little over one year.

DETAILED DESCRIPTION

The present disclosure is directed to shotgun shells comprising abiodegradable powder wad and a biodegradable shot wad, wherein thebiodegradable shot wad surrounds the shot in the shell. In someembodiments, the biodegradable shot wad comprises a biodegradablepolyester. In some embodiments, the biodegradable powder wad physicallyseparates the powder from the shot. In some embodiments, thebiodegradable powder wad comprises a biodegradable polymer (includingnon-plastic polymers) according to the ASTM D6400 standard specificationfor solid material biodegradation by composting. In the embodimentsdescribed herein, the biodegradable powder wad is physically andchemically distinct from the biodegradable shot wad. The biodegradablepowder wad and the biodegradable shot wad are separate or independentcomponents. In some embodiments, upon firing of the shotgun shell from ashotgun having a barrel such that the shot exits the barrel at avelocity exceeding 1,000 feet per second, the biodegradable powder wadstays intact and does not break apart within one meter of exit from thebarrel, and the biodegradable shot wad breaks apart into multiplediscrete pieces within one meter of exit from the barrel.

The present disclosure is also directed to loading environmentallyresponsible shotshells having a multi-component wad system comprising abiodegradable powder wad that stays intact through the firing process,and a distinct biodegradable shot wad that breaks apart within one meterafter being shot out of the barrel.

The present disclosure is also directed to firing environmentallyresponsible shotshells having a multi-component wad system comprising abiodegradable powder wad that stays intact through the firing process,and a distinct biodegradable shot wad that breaks apart within one meterafter being shot out of the barrel.

The term “wad” generally refers to a component of a shotgun shell thatis used to separate the shot from the powder, and/or to provide a sealthat prevents gas from blowing through the shot rather than propellingthe shot out of the shotgun, and/or contain the shotgun shot, and/or toprotect the barrel from the shot, and/or provide cushioning, and/or fillspace in the shell. Commercial wads often consist of three parts: thepowder wad, the cushion, and the shot cup or shot wad. In wad systems,the powder wad, the cushion, and the shot wad may be in separate piecesor can be incorporated into a single component. The wad is stored withina shotgun shell. As used herein, a one-piece wad is a wad that includesboth the powder wad and the shot wad. The wad system described hereinincludes a shot wad and a powder wad which are separate or distinctcomponents. The wad system can be referred to as a two-piece wad,although additional components may be within the shotgun shell.

As shown in FIG. 1, which is a schematic diagram showing components of ashotgun shell 100, the casing 10, here shown to include a brass head 11,contains a powder charge 20 adjacent to a wad system 30. Upon firing,the primer 40 ignites the powder charge 20, which propels the wad system30 and shot 50 through the barrel of the shotgun. The wad system holdsthe shot together as it moves down the barrel after firing of the gun.Both the shot and the wad system tend to travel significant distancesafter leaving the barrel and are often abandoned by the shooter.

The term “wad” includes, but is not limited to, powder wads, over shotwads, cushion wads, and shot wads (including shot pipe wads and shotcups). The powder wad typically provides the gas sealing function, andsuch wads are also referred to as over powder wads, or gas seals. Theshot wad holds the shot together and protects the barrel from the shot,and vice-versa.

Biodegradable shot wads as described herein are a type of shot wad. Inembodiments described herein, the shot wad is not a one-piece wad thatperforms all of the requisite functions of a shotgun wad. Specifically,an independent powder wad is also provided which provides the gassealing function. The shot wad contains and surrounds the shot. In someembodiments, the shot wad is a shot cup, with one closed end (the backend) that is positioned adjacent to the powder wad.

In other embodiments, the shot wad is a shot pipe wad, which has twoopen ends. Many sizes, shapes, and designs are contemplated, althoughthe shot pipe wad has the general shape of a cylindrical pipe. Aphotographic image of one embodiment of a shot pipe wad is shown in FIG.2. As described herein, a “cylindrical” shape does not require a perfectcylinder; instead, an object having a cylindrical shape includesgenerally cylindrical objects such as a beer can, a tree trunk, and apencil. A biodegradable shot pipe wad as described herein can be aperfect cylinder, or it can be tapered, or have a slight barrel shape,or any other suitable variations that have a generally cylindricalshape. For example, the back end of the shot pipe wad (i.e., the endthat is closest to the powder and exits the gun last) can be thickerthan the front end of the wad (i.e., the end that exits the barrelfirst), or the front end of the wad (i.e., the end that exits the barrelfirst) can be thicker than the back end of the shot pipe wad (i.e., theend that is closest to the powder and exits the gun last).

The shot wad can be scored, or cut all the way through in some areas.The shot wad having the shot cup design, the shot pipe wad, or any othershot wad design can include score lines, also called grooves or breaklines. In some embodiments, the score lines (do not extend all the wayto the back end and/or front end of the shot wad. In some embodiments,the score lines can extend along a portion of the length of the shotwad. The score lines can be longitudinally arranged. The shot wad caninclude any number of score lines (e.g., one, two, three, four, five,six, seven, eight, nine, ten, etc.). In some embodiments, the scorelines can extend the entire length of the shot wad. For example, in oneembodiment, in a 12 gauge, biodegradable shot pipe wad having a lengthof 1.7 inches, six evenly spaced score lines are longitudinally arrangedon the inside of the cylinder, extending from one end to the other. Inanother embodiment, in a 12 gauge biodegradable shot pipe wad having alength of 1.7 inches, eight evenly spaced score lines are longitudinallyarranged on the inside of the cylinder, extending a length of 1.6inches, but stopping 0.05 inches from either end of the shot pipe wad.

FIG. 3 is a schematic cutaway diagram showing a shotgun shell with amulti-component wad system as described herein. The casing 10 (cutawayin the diagram to reveal the contents inside the casing) contains apowder charge 20 beneath a multi-component wad system 30. Upon firing,the primer 40 ignites the powder charge 20, which propels the wad system30 and shot 50 through the barrel of the shotgun. The wad system 30includes both a powder wad 36 and a shot wad 37 (also cutaway to revealthe shot inside the shot wad). In this representative embodiment, thecasing 10 includes a brass base 11. The wad system holds the shottogether as it moves down the barrel after firing of the gun. Both theshot and the wad system tend to travel significant distances and areoften abandoned by the shooter.

FIG. 4A and FIG. 4B show photographic images of one embodiment of apowder wad suitable as the powder wad in the multi-component wad systemdescribed herein. The side of the wad shown in FIG. 4A constitutes thebottom of this gas seal wad, and this side would be adjacent to thepowder. The side of the wad shown in FIG. 4B constitutes the top of thethis gas seal wad comprising PBSA, and the shot would be loaded on topof this side of the wad after insertion of a shot wad.

In some embodiments, the powder wad comprises a disc or another flat orthin or round object. In some embodiments, the powder wad comprises aside wall or another retainer or perimeter or barrier. In someembodiments, the powder wad comprises an enclosed or partially enclosedshape. In some embodiments, the powder wad is any shape to perform thefunction of obturating, blocking, or obstructing. Any other wad designsthat provide a gas sealing function are contemplated herein, includinggas seal designs known in the art.

The powder wad can comprise one or more biodegradable polymers. Forexample, the powder wad can be a traditional fiber wad, or felt wad, orcork wad, or nitro wad, or some combination thereof. The powder wads canbe made from one or more materials that perform the function ofseparating the shot from the powder. A wide variety of designs aresuitable. For example, a fiber wad can be combined with a felt wad.Whichever one is directly in contact with the powder would be referredto herein as the powder wad. In all embodiments described herein, apowder wad is combined with a shot wad that contains and surrounds theshot within the hull. Accordingly, a conventional disc-shaped wad madefrom a material such as, for example, felt, cork, fiber or plastic, doesnot constitute a shot wad, irrespective of where it is loaded within theshell, because it would not contain and surround the shot within thehull. Such wads would not protect the gun barrel from being scratched bythe shot when the gun is fired, as the disc-shaped wads do not form aradial barrier between the shot and the casing. Various materials arecontemplated for the shot wad and/or the powder wad as described herein.

Polyhydroxyalkanoates (PHA) are biological polyesters synthesized by abroad range of natural and genetically engineered bacteria as well asgenetically engineered plant crops. In general, a PHA is formed bypolymerization of one or more monomer units inside a living cell. Over100 different types of monomers have been incorporated into PHA polymers(Steinbuchel and Valentin, 1995, FEMS Microbiol. Lett. 128:219-228).Examples of monomer units incorporated in PHAs include2-hydroxybutyrate, lactic acid, glycolic acid, 3-hydroxybutyrate(hereinafter referred to as 3HB), 3-hydroxypropionate (hereinafterreferred to as 3HP), 3-hydroxyvalerate (hereinafter referred to as 3HV),3-hydroxyhexanoate (hereinafter referred to as 3HH), 3-hydroxyheptanoate(hereinafter referred to as 3HHep), 3-hydroxyoctanoate (hereinafterreferred to as 3HO), 3-hydroxynonanoate (hereinafter referred to as3HN), 3-hydroxydecanoate (hereinafter referred to as 3HD),3-hydroxydodecanoate (hereinafter referred to as 3HDd),4-hydroxybutyrate (hereinafter referred to as 4HB), 4-hydroxyvalerate(hereinafter referred to as 4HV), 5-hydroxyvalerate (hereinafterreferred to as 5HV), and 6-hydroxyhexanoate (hereinafter referred to as6HH). 3-hydroxyacid monomers incorporated into PHAs are the (D) or (R)3-hydroxyacid isomer with the exception of 3HP which does not have achiral center.

In some embodiments, the PHA in the methods described herein is ahomopolymer (where all monomer units are the same). Examples of PHAhomopolymers include poly 3-hydroxyalkanoates (e.g., poly3-hydroxypropionate (hereinafter referred to as P3HP), poly3-hydroxybutyrate (hereinafter referred to as PHB) and poly3-hydroxyvalerate), poly 4-hydroxyalkanoates (e.g., poly4-hydroxybutyrate (hereinafter referred to as P4HB), or poly4-hydroxyvalerate (hereinafter referred to as P4HV)) and poly5-hydroxyalkanoates (e.g., poly 5-hydroxyvalerate (hereinafter referredto as P5HV)).

In certain embodiments, the starting PHA can be a copolymer (containingtwo or more different monomer units) in which the different monomers arerandomly distributed in the polymer chain. Examples of PHA copolymersinclude poly 3-hydroxybutyrate-co-3-hydroxypropionate (hereinafterreferred to as PHB3HP), poly 3-hydroxybutyrate-co-4-hydroxybutyrate(hereinafter referred to as PHB4HB), poly3-hydroxybutyrate-co-4-hydroxyvalerate (hereinafter referred to asPHB4HV), poly 3-hydroxybutyrate-co-3-hydroxyvalerate (hereinafterreferred to as PHB3HV), poly 3-hydroxybutyrate-co-3-hydroxyhexanoate(hereinafter referred to as PHB3HH) and poly3-hydroxybutyrate-co-5-hydroxyvalerate (hereinafter referred to asPHB5HV). By selecting the monomer types and controlling the ratios ofthe monomer units in a given PHA copolymer, a range of materialproperties can be achieved.

In some embodiments, mixtures of different PHA polymers can be used. Insome embodiments, amorphous PHA is combined with another PHA polymer.

PBS(x) refers to the polybutylene succinate family of polymers, whichincludes polybutylene succinate and polybutylene succinate copolymersthat can be synthesized via condensation of succinic acid,1,4-butanediol, and one or more additional diacids. For example, adipicacid is the diacid co-monomer that is added to produce PBSA, which isalso referred to as poly(butylene succinate-co-adipate) or polybutylenesuccinate adipate. As contemplated herein, the content of the succinicacid co-monomer in PBS(x) can be between 60% and 100%. Thisconcentration would be 100% when the polymer is PBS (i.e., when there isno co-monomer component), and the concentration of the succinic acidco-monomer can be as low as 60% for copolymers such as PBSA. Asdescribed herein, PBS(c) refers to polybutylene succinate copolymerscontaining a diacid co-monomer other than adipic acid.

For PBSA formulations, mechanical strength initially rises withincreased adipic acid monomer content at very low levels of adipic acidmonomer (e.g., 5% molar levels or less), but then begins to decrease asadipic acid molar levels increase. As the adipic acid monomer contentincreases, the glass transition temperature and melt temperature tend todrop. Moreover, biodegradability increases as the adipic acid monomerconcentration rises (at least through 20% adipic acid monomer content).In general, PBSA has superior biodegradability to PBS.

The shot wad comprises at least one biodegradable polymer. Suitablebiodegradable polymers include polyesters including but not limited toPHA, PBS, PLA, PCL, and PBSA. Thermoplastic starches can be used. Otherbiodegradable polymers, including ones not yet available commercially,could also be used. Blends of materials can be suitable. Thebiodegradable polymer PCL has a lower-than-desired melting point and isnaturally very tough, and would not be a suitable polymer by itself touse to make the shot wad. However, in blends with PHA, for example, itcan be suitable.

Compositions comprising PHA or PHA blends are particularly suitable forthe shot wad because of the biodegradability of PHA, provided the impactresistance is appropriate; that is, the impact resistance must besufficiently high such that the shot wad does not break apart before theshot wad has exited the barrel, but not so high that the shot wad failsto break apart within one meter of leaving the barrel after being fired.Temperature and storage time may have an impact on these properties. Inpreferred embodiments, the biodegradable polymer of the shot wad is abiodegradable polyester polymer.

The powder wad comprises at least one biodegradable polymer. Suitablebiodegradable polymers include polyesters including but not limited toPHA, PBS, PLA, PCL, and PBSA. Compositions comprising PBS(x) blends canbe particularly suitable for the powder wad because of the impactresistance which must be sufficiently high such that the powder wadstays intact while exiting the barrel and during flight. Temperature andstorage time may have an impact on these properties. Compositionscomprising a minor percentage of PHA or PHA blends can be particularlysuitable for the powder wad because of the biodegradability of PHA. Inpreferred embodiments, the biodegradable polymer of the powder wad is abiodegradable polyester polymer.

There are a number of standard tests that measure toughness or impactresistance, but none of them translate perfectly to this applicationrelated to biodegradable wads.

Instead, we have designed a functional test most suitable for theintended application; i.e., firing live shotgun ammunition. A 12 gauge,3″, primed hull is loaded with a suitable powder (e.g., 2.2 grams ofSTEEL® shotshell powder from Alliant Powder), a suitably sizedbiodegradable powder wad, 1¼ ounces of #2 steel shot, and a suitablysized biodegradable shot wad. The shell is cooled to between −20° C. and4° C. and fired with a 12 gauge shotgun equipped with an internalmodified or modified choke at an initial shot velocity (after leavingthe barrel) between 1250 feet per second (fps) and 1500 fps. If the shotwad breaks apart before exiting the barrel, then the shot wadformulation is too brittle. If the biodegradable powder wad does notstay intact, it is not suitable. Another equivalent shell is maintainedat a temperature between 20° C. and 25° C. and fired with the sameequipment. If the shot wad does not break apart (after firing in ahorizontal direction) within one meter of exiting the barrel, then thewad formulation is too tough, and not suitable. For example, manybiodegradable shot wad formulations with the rubbery polymerpolycaprolactone would be too tough.

FIGS. 5-7 show time-series images of different embodiments of shotshellsof the present invention after being fired from a shotgun (taken with anEdgertronic camera at 30,000 frames per second). Depending on a numberof variables (including wad design, wad formulation, outsidetemperature, and loading variables), the biodegradable shot wad canbreak apart almost immediately upon leaving the barrel, or aftertraveling up to one meter out of the barrel.

FIGS. 8-10 show single images of different embodiments of shotshells ofthe present invention after being fired from a shotgun (taken with anEdgertronic camera at 30,000 frames per second). Depending on a numberof variables (including wad design, wad formulation, outsidetemperature, and loading variables), the biodegradable shot wad canbreak apart almost immediately upon leaving the barrel, or after a delayof up to one meter. Cracks can be readily apparent immediately upon exitfrom the barrel (e.g., FIG. 9 and FIG. 10), or not obviously apparent(FIG. 8). The cracks can be large (e.g., see FIG. 9), which can lead toa clamshell fairing effect, or there can be many smaller cracks (seeFIG. 10), which produces different shot patterns when the wad breaksapart in mid-air. In some embodiments, cracks and/or score lines are anintegral part of the powder wad design. In other embodiments, crackingcan occur during the loading process. In all embodiments, the powder waddoes not break apart until it exits the barrel after firing.

The wad system herein described is compatible with various types ofshotgun shells. It is anticipated that the wads will be incorporatedinto shotgun shells used, for example, for waterfowl hunting, claytarget shooting, and other activities. It is envisioned that the wadsdescribed herein can be inexpensively substituted for existing wads,thereby providing the desired degradability without having a substantialadverse impact on the cost. The wads described herein are also suitablefor hunting larger game (e.g., using buckshot loads), smaller game, homedefense, and target shooting (e.g., trap shooting, skeet shooting, andsporting clays), and other purposes for which shotguns are useful.

The biodegradable multi-component wad system can be combined with othershotgun shell loading components in any suitable manner, such othercomponents including other wads as desired (e.g., over shot wad,cushioning wad, filler wad, etc.), any size or suitably shaped hull,primer, powder, shot, buffer, etc. For example, hulls can be for 8 ga,10 ga, 12 ga, 16 ga, 20 ga, 24 ga, 28 ga, 32 ga, or .410 bore shotguns,and can be any appropriate length (e.g., including but not limited to 2½inch, 2¾ inch, 3 inch, 3½ inch) and shape (e.g., straight sides,tapered). Any suitable shot material can be used (including but notlimited to lead, steel, tungsten, bismuth, and alloys and combinationsthereof), in any suitable size (including but not limited to the rangefrom No. 9 shot all the way to 000 buckshot), in any shape (includingbut not limited to spherical, rough spherical, and hexagonal), and inany payload.

The biodegradable wads described herein can include additives includingbut not limited to other polymers (including non-biodegradablepolymers), lubricants, release agents, plasticizers, impact modifiers,nucleating agents, colorants, stabilizers, photodegradation agents,fillers, and plasticizers. In all such compositions, the biodegradablepolymer content remains above 50% by weight of the wad, preferably above60% by weight, more preferably above 70% by weight, and sometimes above80% by weight of the wad.

In some embodiments, the shot wad comprises a biodegradable material. Insome embodiments, the shot wad comprises a biodegradable polymer. Insome embodiments, the shot wad comprises a biodegradable polyester. Insome embodiments, the shot wad comprises PHA. In some embodiments, theshot wad comprises two or more biodegradable polymers (e.g., twobiodegradable polymers, three biodegradable polymers, four biodegradablepolymers, or five biodegradable polymers). In some embodiments, the shotwad comprises a biodegradable polymer in a percentage by weight greaterthan 50%, greater than 55%, greater than 60%, greater than 65%, greaterthan 70%, greater than 75%, greater than 80%, greater than 85%, greaterthan 90%, greater than 95%, between 40% and 60%, between 50% and 70%,between 60% and 80%, between 70% and 90%, between 80% and 100%,approximately 50%, approximately 55%, approximately 60%, approximately65%, approximately 70%, approximately 75%, approximately 80%,approximately 85%, approximately 90%, approximately 95%, orapproximately 100%, or ranges incorporating any of the foregoing values.In some embodiments, the shot wad comprises biodegradable polymers in apercentage by weight of the total wad greater than 50%, greater than55%, greater than 60%, greater than 65%, greater than 70%, greater than75%, greater than 80%, greater than 85%, greater than 90%, greater than95%, between 40% and 60%, between 50% and 70%, between 60% and 80%,between 70% and 90%, between 80% and 100%, approximately 50%,approximately 55%, approximately 60%, approximately 65%, approximately70%, approximately 75%, approximately 80%, approximately 85%,approximately 90%, approximately 95%, or approximately 100%, or rangesincorporating any of the foregoing values.

In some embodiments, the powder wad comprises a biodegradable material.In some embodiments, the powder wad comprises a biodegradable polymer.In some embodiments, the powder wad comprises a biodegradable polyester.In some embodiments, the powder wad comprises PBS(x). In someembodiments, the powder wad comprises a non-plastic biodegradablematerial. In some embodiments, the powder wad comprises two or morebiodegradable polymers (e.g., two biodegradable polymers, threebiodegradable polymers, four biodegradable polymers, or fivebiodegradable polymers). In some embodiments, the powder wad comprises abiodegradable polymer in a percentage by weight greater than 50%,greater than 55%, greater than 60%, greater than 65%, greater than 70%,greater than 75%, greater than 80%, greater than 85%, greater than 90%,greater than 95%, between 40% and 60%, between 50% and 70%, between 60%and 80%, between 70% and 90%, between 80% and 100%, approximately 50%,approximately 55%, approximately 60%, approximately 65%, approximately70%, approximately 75%, approximately 80%, approximately 85%,approximately 90%, approximately 95%, or approximately 100%, or rangesincorporating any of the foregoing values. In some embodiments, thepowder wad comprises biodegradable polymers in a percentage by weight ofthe total wad greater than 50%, greater than 55%, greater than 60%,greater than 65%, greater than 70%, greater than 75%, greater than 80%,greater than 85%, greater than 90%, greater than 95%, between 40% and60%, between 50% and 70%, between 60% and 80%, between 70% and 90%,between 80% and 100%, approximately 50%, approximately 55%,approximately 60%, approximately 65%, approximately 70%, approximately75%, approximately 80%, approximately 85%, approximately 90%,approximately 95%, or approximately 100%, or ranges incorporating any ofthe foregoing values. The present application is related to U.S. patentapplication Ser. No. 14/303,496, filed Jun. 12, 2014, which claimspriority under 35 U.S.C. § 119(e) to U.S. Provisional Patent ApplicationNo. 61/835,053, filed Jun. 14, 2013, the disclosure of each applicationis incorporated by reference herein in its entirety.

In some embodiments, the shot wad and/or the powder wad can comprise amaterial without a non-degradable reinforcing structure such as fibers.In some embodiments, the shot wad and/or the powder wad can comprise amaterial without a non-degradable matrix or binder.

Some manufacturers claim that their plastic wads are degradable.However, these wads often consist of non-degradable plastic in a matrixof degradable materials. The degradable materials break down leavingbehind small fragments of non-degradable plastic. Non-degradableplastics can break apart over time into smaller and smaller pieces.These microplastics pose substantial risk to the entire aquatic foodweb.

Microplastic fragments range in size from a few to five hundredmicrometers. Due to their abundance, microplastics have become asignificant marine debris concern worldwide. Once microplastics enterthe aquatic ecosystem, their buoyancy, size, and longevity within thewater column lead to ongoing problems. Microplastics can be ingested byboth pelagic and benthic organisms. Studies have shown microplasticuptake by marine species including filter-feeders, detritivores, depositfeeders, and planktivores. Microplastics accumulate in the fatty tissueof aquatic species. The fatty tissues become more concentrated withmicroplastics as organisms mature, posing a significant risk for higherorder species. For instance, studies have shown the tropic transfer ofmicroplastics from mussels to the crabs that feed on them (Farrell, P.and K. Nelson. 2013. Trophic level transfer of microplastic: Mytilusedulis (L.) to Carcinus maenas (L.). Environmental Pollution 177: 1-3).

An increasing concern is that microplastics can sorb and concentratecontaminants and pollutants. Therefore, not only are microplasticsaccumulating in the tissues of organisms, but pollutants are alsoaccumulating. These pollutants are transported throughout the food webto organisms at various trophic levels. Therefore, non-biodegradableshotgun wads ultimately contribute to the destruction of the aquaticecosystem.

Additionally, many non-biodegradable polymers such as polyethylenefloat, causing the plastic wad to remain suspended in the water columnand potentially travel long distances. In contrast, many commerciallyavailable biodegradable polyesters (e.g., PBSA, PBS, PHA, PLA) havespecific gravities of 1.2 or higher, giving them a tendency to sink whendischarged into an aquatic environment. Preferred compositions ofbiodegradable shot wads and biodegradable powder wads have specificgravities of at least 1.1 and are negatively buoyant. Negative buoyancyreduces the potential distance that the biodegradable wads can travelwhen they are in an aquatic environment. Further, the negative buoyancyallows the degradable wad to be continuously submerged, which canincrease the rate of degradation for PHA and potentially other polymers.

PHA, PBSA, PLA, PBS, and some PBS(c) polymers eventually break down intobenign monomers, oligomers, and byproducts. Many conventional plasticsdo not degrade into benign monomers and oligomers in terrestrial oraquatic environments.

Note that a spent biodegradable wad may be ejected onto land or water,and could move from one environment to the other. There are manyvariables that impact when and if a spent shotgun wad will degrade inthe environment. The time to degradation is complicated by thevariability in different micro-environments around the planet. Forexample, underwater aquatic environments can have substantialvariability in terms of pressure, temperature, salinity, andbiodiversity, all of which can impact the rate of degradation. Further,degradation is not always consistent throughout the component. Forexample, the injection molding process can have an influence. Moderatingthe rate of degradation of a shotgun wad can be achieved, for example,by altering any of a number of factors, including but not limited to:the molecular weight of the polymer, the choice of or concentration ofplasticizer or other additives, a coating on the polymer, surfaceimperfections, or the design of the biodegradable wad, in particular itsthickness.

The biodegradable wads described herein break down in the environmentinto environmentally benign components, sometimes (depending on theenvironment) in less than a year, but not always. Ammunition shot fromthe deck of a cruise ship or aircraft carrier over the deep ocean willresult in a spent wad that will sink to the bottom of the ocean, anenvironment that may be anoxic and might not be conducive forbiodegradation (e.g., shipwrecked wooden boats can remain remarkablywell-preserved after hundreds of years in such environments). Otherenvironments might also not be particularly favorable forbiodegradation, so we cannot unequivocally state a time in which thewads will always biodegrade. We can, however, be confident that undermost relevant conditions, the biodegradable shot pipe wads willbiodegrade reasonably quickly without negatively impacting theenvironment.

Among the biodegradable polyesters PHA, PBS, PBSA, PCL, and PLA, thematerial PHA generally biodegrades the most rapidly in saltwaterenvironments. Some preferred biodegradable wad compositions comprise atleast 5% PHA, and include compositions wherein PHA is the onlybiodegradable polymer. In some embodiments, the powder wad comprises aminor percentage of PHA. In some embodiments, the shot wad comprises amajor percentage of PHA. In some embodiments, both the shot wad and thepowder wad are primarily composed of PHA, but utilize differentformulations of PHA. For example, in some embodiments, the powder wadhas a much high proportion, relative to the shot wad, of amorphous PHA,which toughens the resulting material.

In some embodiments, the powder wad comprises PHA in a percentage byweight less than 25%, less than 20%, less than 15%, less than 10%, lessthan 5%, less than 1%, greater than 0%, greater than 1%, greater than3%, greater than 5%, greater than 10%, greater than 15%, greater than20%, greater than 25%, between 0.1% and 5%, between 5% and 10%, between10% and 15%, between 1% and 20%, between 1% and 30%, approximately 0.1%,approximately 1%, approximately 5%, approximately 10%, approximately15%, approximately 20%, approximately 25%, or approximately 30%, orranges incorporating any of the foregoing values In some embodiments,the powder wad consists essentially of a biodegradable polymer otherthan PHA and PHA. In some embodiments, the weight ratio of abiodegradable polymer other than PHA to PHA in the powder wad is greaterthan 4:1 (e.g., greater than 5:1, greater than 6:1, greater than 7:1,greater than 8:1, greater than 9:1, greater than 10:1, greater than11:1, greater than 12:1, greater than 13:1, greater than 14:1, orgreater than 15:1, or ranges incorporating any of the foregoing values).

The term “effective amount,” as used herein, refers to that amount ofPHA that imparts a biodegradation effect on a PBSA component. Forexample, an effective amount can refer to the amount of PHA thatimproves a biodegradation by at least 1%, at least 5%, at least 10%, atleast 15%, at least 20%, at least 25%, at least 30%, at least 35%, atleast 40%, at least 45%, at least 50%, at least 55%, at least 60%, atleast 65%, at least 70%, at least 75%, at least 80%, at least 85%, atleast 90%, at least 95%, or at least 100%, or ranges incorporating anyof the foregoing values. In some embodiments, an improvement in abiodegradation can be the reduction of days before complete degradation.In some embodiments, an improvement in fracturing of a spent wad is animprovement in degradation.

The biodegradable wads can be produced using any suitable productionprocess known in the art. For example, they can be produced by injectionmolding, or could be produced via extrusion. In some embodiments, anextrusion process could have significant cost advantages relative toinjection molding, particularly for a product that is almost perfectlycylindrical. For example, the wads can be produced by injection molding,low pressure molding, gas-assist molding, structural foam molding,coinjection, reaction-injection molding, blow molding, rotationalmolding, thermoforming, compressing molding, etc.

Through field testing, it has been discovered that biodegradable shotwads as described herein are sufficiently tough to withstand beingdischarged from a shotgun when combined with a functional biodegradablepowder wad, as further described in the examples below. These shot wadsfragmented once outside the barrel, visually fragmenting within onemeter from the barrel when viewed with a high-speed camera. These shotwads often broke into longitudinal pieces along score lines and traveledbetween about 10 yards and 30 yards from the barrel. Typically, thebiodegradable powder wads, which stayed intact, traveled significantlyfurther from the barrel. Importantly, the biodegradable shot wads notonly provide an environmental benefit, but also provide superior shotpatterns to conventional wad designs, as described below. It is notinherent that biodegradable shot wads, including those made from arelatively brittle biodegradable polymer such as PHA, will break apartwithin one meter of leaving the barrel. Depending on the formulation anddesign, we produced and recovered many intact PHA shot wads that did notbreak apart within one meter of leaving the barrel. This is obviouslynot desirable, as the shot is not cleanly released, and theshot-containing shot wad can tumble in flight, leading to erraticpatterns. Accordingly, it is crucial to utilize a method wherein thebiodegradable shot wad breaks apart within one meter of leaving theshotgun barrel when fired at an initial exit speed exceeding 1,000 feetper second.

By utilizing a shot wad comprising a biodegradable polymer, for examplea biodegradable polyester, including, for example, a biodegradablepolyester selected from the group consisting of PHA, PBSA, PBS, PBS(x),PCL, PLA, and blends thereof, the shot wad performs its intendedfunction of protecting the barrel/shot, and also provides enhancedperformance while substantially decreasing the environmental footprintof sportsmen. When said shot wad is combined with a biodegradable powderwad that stays intact throughout the firing process, in contrast to theshot wad that breaks apart within one meter of leaving the barrel afterfiring, the entire system is biodegradable and provides outstandingperformance.

Particular advantages of this wad system in a shotgun shell can include,but are not limited to advantages related to the biodegradable powderwad: (i) by staying intact, the powder wad can perform the gas sealingfunction of gas seals of commercially available ammunition; (ii) bystaying intact, the powder wad can perform as well as, and in somecases, better than commercial ammunition; and (iii) by staying intactduring flight but fragmenting during degradation, the powder wad canadhere to one or more standards for biodegradable without impactingperformance.

In some embodiments, the powder wad has the unexpected advantage ofbetter performance. The powder wad has as good as or better results thancommercial ammunition, as described herein. Compared with commercialammunition that utilizes conventional plastic wads, ammunition thatincorporates the wad system described herein often provides more shot ontarget, including more consistent coverage in the target zone, resultingin a higher kill percentage. Many sportsmen have turned away from“degradable” shotgun shells such as paper wads since these wads do notperform as well as non-degradable plastic wads. However, as disclosedherein, the biodegradable wad system has better results based on patternanalysis software. In an example below, ammunition incorporating thebiodegradable wad system described herein has a significantly higherpercentage of shot on target compared with commercial ammunition.

In some embodiments, the powder wad has the unexpected advantage,relative to other biodegradable polymers, of staying intact when used asthe gas sealing wad. In an example below, the powder wads stayed intact.The powder wad can be recovered intact downrange. This is in contrast tothe shot wad which fragmented. The fragments of the shot wad traveledless distance than the powder wad. The shot wad may stay intact untilexiting the barrel, but fragmentation occurs very soon thereafter. Thepowder wad can stay intact for the entire flight duration and landing.The powder wad is designed not to fragment during and immediately afterbeing fired. In some embodiments, the powder wad contains a minorpercentage of PHA, and is designed to stay intact during and immediatelyafter being fired. In some embodiments, the powder wad contains a minorpercentage of PHA, and is designed to stay intact during the duration ofthe flight but fragment quickly during degradation.

In some embodiments, the powder wad with a minor percentage of PHA hasthe unexpected advantage of outperforming wads of only one biodegradablepolymer. In an example below, wads with a compounded formula of 9:1weight ratio of PBSA to PHA outperformed wads in which PBSA was the onlybiodegradable polymer. In some embodiments, the powder wad with a minorpercentage of PHA had the unexpected advantage of greater resistance tocracking. In some embodiments, the powder wad with a minor percentage ofPHA had the unexpected advantage of a higher average velocity. In someembodiments, the powder wad with a minor percentage of PHA had theunexpected advantage of better shot patterns.

In some embodiments, the powder wad with a minor percentage of PHA hasthe unexpected advantage of degrading faster than wads of only onebiodegradable polymer. PHA has a specific gravity greater than 1 causingits tendency to sink, which can reduce the likelihood of adsorbingfloating organic toxins, reduce the likelihood of migrating longdistances (e.g., into the middle of the Pacific Ocean), reduce thelikelihood of being consumed by sea birds, and accelerate the rate ofbiodegradation. The minor percentage of PHA has the unexpected advantageof increasing degradability. The powder wad with minor percentage of PHAhas the unexpected advantage of increasing degradability in salt water.

In some embodiments, the powder wad can advantageously perform in avariety of conditions. In an example below, the powder wad can performat a variety of temperatures. The powder wad can perform at a variety ofambient environments, regardless of humidity or due point. The powderwad can perform in a variety of weather conditions and perform as wellas commercial ammunition in rain, sleet, hail, snow, wind, extreme heat,or other conditions. Further, the powder wads are as functional ascommercially available wads and are sufficiently durable to withstandbeing discharged from a shotgun. In some embodiments, the powder waddoes not undergo a structural change upon firing, allowing the wads tostay primarily intact within the barrel and during flight. In someembodiments, the powder wad, such as the powder wad with a minorpercentage of PHA, then breaks apart into small fragments duringdegradation, or erodes such that small fragments are removed from themain body of the wad.

In some embodiments, the powder wad has the unexpected advantage offaster degradation. The powder wad can degrade in an aquaticenvironment. The powder wad can degrade within a short period of time,(e.g., six months, twelve months, eighteen months, or twenty-fourmonths, or ranges incorporating any of the foregoing values). The powderwad can degrade in various salinities. The powder wad can degrade by apercentage weight (e.g., about 2%, about 5%, about 10%, about 15%, about20%, about 25%, about 30%, about 35%, about 40%, about 45%, about 50%,about 55%, about 60%, between 1% and 5%, between 5% and 10%, between 10%and 15%, between 15% and 20%, between 20% and 25%, between 25% and 30%,between 30% and 35%, between 35% and 40%, between 40% and 45%, between45% and 50%, between 50% and 55%, between 55% and 60%, greater than 5%,greater that 10%, greater than 15%, greater than 20%, greater than 25%,greater than 30%, greater than 35%, greater than 40%, greater than 45%,greater than 50%, greater than 55%, or greater than 60%, or rangesincorporating any of the foregoing values) with a certain period of time(e.g., 1 month, 2 months, 3 months, 4 months, 5 months, 6 months, 7months, 8 months, 9 months, 10 months, 11 months, or 12 months, orranges incorporating any of the foregoing values).

The powder wad can degrade by a percentage weight (e.g., about 25%,about 30%, about 40%, about 50%, about 55%, about 60%, about 70%, about90%, about 100%, 100%, between 25% and 50%, between 40% and 60%, between60% and 65%, between 65% and 70%, between 70% and 75%, between 75% and80%, between 80% and 85%, between 85% and 90%, between 90% and 95%,between 95% and 100%, greater than 50%, greater than 55%, greater than60%, greater than 65%, greater than 70%, greater than 75%, greater than80%, greater than 85%, greater than 90%, or greater than 95%, or rangesincorporating any of the foregoing values) with a certain period of time(e.g., 12 month, 13 months, 14 months, 15 months, 16 months, 17 months,18 months, 19 months, 20 months, 21 months, 22 months, 23 months, 24months, 25 months, 26 months, 27 months, 28 months, 29 months, 30months, 31 months, 32 months, 34 months, 35 months, or 36 months, or 37months, or 38 months, or 39 months, or 40 months, or rangesincorporating any of the foregoing values).

Particular advantages of this wad system in a shotshell can include, butare not limited to, advantages related to the biodegradable shot wad:(i) by breaking apart into multiple pieces, the biodegradable shot wadis less visually unappealing, as it is less obvious to the naked eye;(ii) by breaking apart into multiple pieces, more surface area of thebiodegradable shot wad is exposed, which tends to increase the rate ofbiodegradation; (iii) by breaking apart into multiple pieces, thebiodegradable shot wad can be less likely to cause injuries if ingestedby an animal; and (iv) by breaking apart into multiple pieces, thebiodegradable shot wad provides a cleaner release of the shot thantypical prior art plastic wads, all the while the powder wad staysintact and efficiently contains the expanding gases to propel the shot.

In some embodiments, the shot wad can be advantageously produced in anumber of wad configurations. The shot wad can be used in combinationwith various powder wads of different sizes, materials inconfigurations. The shot wad can be made from PHA and loaded withdifferent powder wads comprising biodegradable plastic or biodegradablenon-plastic materials. The quantity of powder and shot can vary, as wellas shot sizes. The biodegradable shot wad in combination with abiodegradable powder wad can advantageously produce as good as or bettershot patterns as commercial ammunition. The wad systems do not usuallyproduce inferior shot patterns, and in some cases can produce more shoton target, and/or more consistent coverage in the target zone, resultingin a higher kill percentage. In some embodiments, the ammunition using awad system with a biodegradable non-plastic powder wad has a loweraverage velocity than otherwise equivalent ammunition (i.e., equivalentshot and powder) using a wad system with a biodegradable plastic powderwad comprising a plastic material.

In some embodiments, the shot wad has the unexpected advantage of fasterdegradation. The shot wad can degrade in an aquatic environment. Theshot wad can degrade within a short period of time, (e.g., six months,twelve months, eighteen months, twenty-four months, etc.). The shot wadcan degrade in various salinities. The shot wad can degrade by apercentage weight (e.g., about 5%, about 10%, about 15%, about 20%,about 25%, about 30%, about 35%, about 40%, about 45%, about 50%, about55%, about 60%, between 1% and 5%, between 5% and 10%, between 10% and15%, between 15% and 20%, between 20% and 25%, between 25% and 30%,between 30% and 35%, between 35% and 40%, between 40% and 45%, between45% and 50%, between 50% and 55%, between 55% and 60%, greater than 5%,greater that 10%, greater than 15%, greater than 20%, greater than 25%,greater than 30%, greater than 35%, greater than 40%, greater than 45%,greater than 50%, greater than 55%, greater than 60%, or rangesincorporating any of the foregoing values) within approximately 4 months(e.g., 1 month, 2 months, 3 months, 4 months, 5 months, 6 months, 7months, 8 months, or ranges incorporating any of the foregoing values)

The shot wad can degrade by a percentage weight (e.g., about 10%, about15%, about 20%, about 25%, about 30%, about 35%, about 40%, about 45%,about 50%, about 55%, about 60%, about 70%, about 90%, about 100%, 100%,between 1% and 20%, between 20% and 30%, between 50% and 55%, between55% and 60%, between 60% and 65%, between 65% and 70%, between 70% and75%, between 75% and 80%, between 80% and 85%, between 85% and 90%,between 90% and 95%, between 95% and 100%, greater than 10%, greaterthan 20%, greater than 30%, greater than 40%, greater than 50%, greaterthan 55%, greater than 60%, greater than 65%, greater than 70%, greaterthan 75%, greater than 80%, greater than 85%, greater than 90%, orgreater than 95%, or ranges incorporating any of the foregoing values)within approximately 12 months (e.g., 8 months, 9 months, 10 months, 11months, 12 month, 13 months, 14 months, 15 months, or 16 months, orranges incorporating any of the foregoing values).

There are additional unexpected advantages for the multi-component wadsystem described herein relative to a one-piece, unitary wad system. Aone-piece wad system is substantially cheaper, with potentially reducedcosts for loading (at least one fewer component than a two-piece wadsystem) and reduced costs to produce the wads (injection molding istypically priced on a per piece basis, so producing two small plasticparts is substantially more expensive than producing one slightly largerpart). Yet in spite of the cost disadvantage, the multi-component wadsystem and methods described herein are advantageous relative to aone-piece wad system that also seeks to take advantage of the cleanrelease afforded by the wad breaking up post-barrel. The problem with aone-piece wad system that breaks up post-barrel is that the formulationcan lead to either (i) premature cracking in the gas sealing portion ofthe one-piece wad, or (ii) failure of the wad to break up after leavingthe barrel. In the former case, if the gas sealing portion iscompromised, then after firing the shell, the rapidly expandingpropulsive gases can blow through the gas sealing wad portion, reducingthe efficiency of the shell and compromising performance, which canlead, for example, to wounded waterfowl that do not fall close enough tothe hunter to be recovered. In the latter case, if the formulation istoo tough and the wad does not break up, then shot accuracy andpatterning can be negatively impacted. While it is possible to designand formulate a one-piece wad that performs in the desired manner bybreaking apart after leaving the barrel, there is a small margin forerror. Variability in the injection molding temperature, or changes inthe wad over time, for example, due to slow crystallization of PHA,could easily exceed the small margin for error, yielding poor productand disappointed users. Unfortunately, this single-wad system is not asrobust, not as consistent, and is less commercially viable, than themulti-component wad system described herein, in spite of the costdisadvantage associated with the multi-component wad system.

EXAMPLES

Plastic resins can be obtained from numerous suppliers. For example, PBSand PBSA can be obtained from Showa Denko K.K. in Tokyo, Japan); PHA canbe obtained from Danimer Scientific in Bainbridge, Ga.; PLA can beobtained from NatureWorks in Minnetonka, Minn.; and PCL can be obtainedfrom Perstorp in Warrington, England. Plastic resins can also beobtained from other suppliers.

Example 1. Formulations of PBSA (BIONOLLE™ 3001 MD, made by Showa DenkoK.K. in Tokyo, Japan) were utilized to form powder wads. Primed 3-inchhulls were loaded with powder, a PBSA powder wad, a shot wad using ashot cup design that was injection molded with a PHA formulation (MIREL®P1004, made by Metabolix Inc. in Cambridge, Mass.) and 1¼ ounces of #2steel shot, then crimped. The shotgun shells were fired from a shotgunat targets to compare shot patterns with commercial ammunition.Performance was as good as or better than comparable commercialammunition that was tested, including comparable average speed, based onhaving more shot on target and a higher kill percentage as determinedusing pattern analysis software (Shotgun Analyzer software availablefrom Target Telemetrics in Martin, Mich.).

Example 2. Formulations of PBSA were utilized to form gas seals for 12gauge shotguns. The PBSA gas seals, with a length of approximately 8 mm,were loaded into shells with powder, #2 steel shot (1¼ ounces), and abiodegradable shot pipe wad (approximately 44 mm in length having aslightly tapered design with an average wall thickness of approximately1.4 mm) made from a polyhydroxyalkanoate polymer designed and formulatedto fracture after leaving the shotgun barrel upon firing. An exemplaryPHA shot pipe wad, with longitudinal score lines to facilitatepatterned, post-barrel fracture, is shown in FIG. 2.

Sufficient powder was used to generate an average velocity of 1338 fps,as measured using an Edgertronic high-speed camera.

FIG. 5 shows a time series set of images from one such shot, showing theflash of the gun, the emergence of the shot and wad, and then thefragmentation of the shot pipe wad soon after it leaves the barrel. Incontrast to the shot pipe wad, the gas seal wad stays intact. FIG. 5shows a PHA shot wad breaking into many pieces and a PBSA gas sealintact. FIG. 5 shows early breakup of the PHA shot wad, but the wad isstill intact inside barrel and immediately upon exit of the barrel.

FIG. 6 shows a time series set of images from another such shot, showingthe flash of the gun, the emergence of the shot and wad, and then thefragmentation of the shot pipe wad after leaving the barrel, in thiscase, with complete breaking up of the shot pipe wad occurring more than50 cm downfield. FIG. 6 shows an intact PBSA gas seal and a PHA shot wadthat breaks apart downfield.

Shot patterns were compared to a commercial 12 gauge, 1¼ ounce, #2 steelshot load using a test pattern at 40 yards, and fired from a shotgunequipped with an Improved Modified Choke. A significantly higherpercentage of shots (88%) hit a 4 ft.×4 ft. target using thebiodegradable ammunition described herein relative to the commerciallyavailable product, and a significantly higher percentage of shots (56%)fell within a central 30-inch diameter circle (the commercial productpercentages were 75% and 41%, respectively). Gas seals stayed intact andwere found downrange, while the shot pipe wad broke apart after exitingthe barrel, and fragments thereof were found not as far downrange. Nosignificant gas blowthrough was observed with any of the shots.

Example 3. Biodegradable gas pipe wads were made from a PHA formulationand loaded into shells with a series of different powder wads, includingwool felt, cork, fiber, nitro cards (obtained from Ballistics Products),beeswax (obtained from one of the inventor's hives), and combinationsthereof. The quantity of powder and shot varied as different types ofloads were loaded, and shot sizes varied as well. Patterns wereexcellent, and velocities were acceptable, although on averagevelocities were nearly 10% lower than when otherwise equivalent loadswere shot with a high-quality, obturating, plastic powder wad (e.g., the12 ga obturator gas seal available from Ballistics Products) rather thanthe powder wads made from the natural materials described above. FIG. 7shows a time-series image of one of these loads being fired.

Example 4. Formulations of PBSA (made from BIONOLLE™ 3001 MD, availablefrom Showa Denko K.K. in Tokyo, Japan) were utilized to form gas sealsfor 12 gauge shotguns. The PBSA gas seals were loaded into shells withpowder, #2 steel shot (1⅜ ounces), and a shot pipe wad made from apolyhydroxy alkanoate polymer designed and formulated to fracture afterleaving the shotgun barrel upon firing. Sufficient powder was used togenerate an average velocity of 1514 fps, with 84% of the shots hittinga 48 inch square target at 40 yards, and 44% within a 30-inch diametercircle.

Example 5. Formulations of PBSA (made from BIONOLLE™ 3001 MD, availablefrom Showa Denko K.K. in Tokyo, Japan) were utilized to form gas sealsfor 12 gauge shotguns. The PBSA gas seals were loaded into shells withpowder, nine to eleven pellets of 00′ shot, a shot pipe wad made from aPHA polymer designed and formulated to fracture after leaving theshotgun barrel upon firing, a filler wad, and optionally buffer (to fillin spaces between the shot) and optionally a cushion wad. Notsurprisingly, shot patterns improved when using buffer; in this case, abuffer comprising PHA powder. The buffer can include any materialincluding those disclosed herein. In some embodiments, the bufferdegrades into environmentally benign components.

Example 6. Shot wads comprising PHA, suitable as part of amulti-component wad system described in other examples and having a shotcup design with one closed end, were injection molded and tested forbiodegradability. Groups of three wads were placed in 250 micron meshbags. The bags were tied shut using cable ties, and a lead weight wasattached if the bag was to be submerged. The bags of wads were put invarious locations around the Chesapeake Bay watershed in Virginia, andtested after roughly four months to assess biodegradation by weight. Toperform the testing, the wads were cleaned, dried in an oven, andweighed. The wads were then re-deployed in the same places for anadditional year, then tested again. Note that this process reducesbiodegradation relative to wads that are just left in the environmentfor the entire time, as there is a ramp-up phase for biodegradation andthe rinse/clean process necessitates a repeat of the ramp-up phase. Theresults are provided in Table 1 below. Most of the wads were immersed inwater (of various salinities), although some wads were located in tidalareas that were sometimes dry, and one set of wads was placed on seasideriprap that is normally dry (and is a poor environment forbiodegradation). The percentage weight losses are the average of eachgroup of three wads at each location.

As is apparent in Table 1 below, the wads biodegraded well infreshwater, brackish, and saltwater environments. An image of thedegraded wads (wads from the VIMS Beachside location in the table belowafter the second test and a total of 16 months in the field over twotesting periods) is provided in FIG. 11, which show the increasingfrailty and reduction in material along the walls of the cup portion ofthe wad.

TABLE 1 % Weight Loss % Weight Loss Location Submerged? Salinity (ppt)After 4 months After 12+ months Guthrie Creek Submerged 9 86 LakeMatoaka Submerged fresh 21 72 Crim Dell Submerged fresh 23 59 Cedar BushTidal 17 58 n/a, bag ripped College Creek Submerged 5 13 80 VIMSTeaching Marsh Submerged 5 5 27 Wachapreague Submerged 32 13 VIMSbeachside Submerged 17 16 66 VIMS riprap NOT n/a 11 12 Seawater fishtank Submerged 20 44 100 

Additionally, powder wads made from PBSA were fired, recovered, weighed,then deployed in 250 micron mesh bags in many of the same freshwater andsaltwater environments. After waiting for one month, the wads werecleaned, dried, and weighed. No significant decomposition was observed.After waiting between 9 and 11 months, the powder wads were cleaned,dried, and weighed. The percentage weight loss at this time ranged from2% to 6%, depending on the environment. This is consistent with atypically longer incubation period for PBSA than PHA.

Example 7. Primed hulls were loaded with powder, a biodegradable powderwad, a biodegradable shot wad, and 1⅜ ounces of #2 steel shot, thencrimped, and then sealant was applied. The loads were then fired from ashotgun equipped with either a full, modified, or improved cylinderchoke. The powder wads were designed to be very short in height, therebytaking up a minimum amount of room in the shell to comfortably allowloading of increased amounts of powder and shot. After firing therounds, the spent powder wads were recovered. In most cases, the wadshad been compromised, with slight pinholes or cracks at the weakestpoint.

Surprisingly, loads with powder wads made from a compounded formulationcomprising a 90:10 weight ratio of PBSA to PHA outperformed loads withpowder wads made from a formulation in which PBSA was the onlybiodegradable polymer. In general, the area of cracking was smaller, theaverage velocity was higher, and a higher average pellet density withina 30-inch circle (40-yard target) was obtained for loads utilizing thepowder wads made from a blended mixture of PBSA and PHA. Moreover, thesewads from a PHA/PBSA blend may have enhanced degradability, particularlyin salt water, relative to otherwise identical wads in which PBSA is theonly biodegradable polymer.

Example 8. Primed 3-inch hulls were loaded with powder, a biodegradablepowder wad, a biodegradable shot wad, and 1¼ ounces of either #2, #3,#5, or #7 steel shot, then crimped. The loads were then fired from ashotgun equipped with a modified choke.

Example 9. Primed 3-inch hulls were loaded with 2.2 grams powder, abiodegradable

PBSA powder wad, a biodegradable shot wad formulated from PHA, and 1¼ounces of #2 steel shot, then crimped. The loads were cooled to −16° C.,0° C., or kept at ambient temperature. Shot velocities were averagedover numerous shots, and no significant differences were observed inshot velocities based on shell temperatures. The number of shot pelletshitting within a 30-inch circle at a distance 25 yards from the end ofthe barrel was recorded. The average percentage of shot hitting withinthe 30-inch circle was 96% for shells cooled to 16° C. or 0° C., and 98%for shells maintained at ambient temperature (about 30° C.).

INCORPORATION BY REFERENCE

All publications, patents, and patent applications cited herein arehereby expressly incorporated by reference in their entirety and for allpurposes to the same extent as if each was so individually denoted.

EQUIVALENTS

While specific embodiments of the subject invention have been discussed,the above specification is illustrative and not restrictive. Manyvariations of the invention will become apparent to those skilled in theart upon review of this specification. The full scope of the inventionshould be determined by reference to the claims, along with their fullscope of equivalents, and the specification, along with such variations.

The articles “a” and “an” are used herein to refer to one or to morethan one (i.e. to at least one) of the grammatical object of thearticle. By way of example, “a wad” means one wad or more than one wad.

Any ranges cited herein are inclusive.

1-30. (canceled)
 31. A shotgun shell comprising: a biodegradable shotwad configured to be confined within a shotgun hull; a biodegradablepowder wad configured to be confined within said shotgun hull; whereinsaid biodegradable powder wad is separate and uncoupled from saidbiodegradable shot wad within said shotgun hull; wherein saidbiodegradable shot wad at least partially surrounds shot within saidshotgun hull; wherein said biodegradable powder wad physically separatespowder from said shot within said shotgun hull; wherein saidbiodegradable shot wad comprises a biodegradable material; wherein saidbiodegradable powder wad comprises a biodegradable material; whereinupon firing of said shotgun shell, said biodegradable shot wad isconfigured to fragment into multiple discrete pieces during flight orlanding; and wherein upon firing of said shotgun shell, saidbiodegradable powder wad is configured to stay intact during flight andlanding.
 32. The shotgun shell of claim 31, wherein said biodegradableshot wad comprises a biodegradable polymer that satisfies the ASTM D6400standard (2004).
 33. The shotgun shell of claim 31, wherein saidbiodegradable shot wad comprises a biodegradable polyester.
 34. Theshotgun shell of claim 31, wherein said biodegradable powder wadcomprises a biodegradable polyester.
 35. The shotgun shell of claim 31,wherein upon firing of said shotgun shell from a shotgun having a barrelsuch that said shot exits said barrel at a velocity exceeding 1,000 feetper second, said biodegradable powder wad stays intact and does notbreak apart within one meter of exit from said barrel.
 36. The shotgunshell of claim 31, wherein upon firing of said shotgun shell from ashotgun having a barrel such that said shot exits said barrel at avelocity exceeding 1,000 feet per second, said biodegradable shot wadfragments into multiple discrete pieces within one meter of exit fromsaid barrel.
 37. The shotgun shell of claim 31, wherein saidbiodegradable powder wad comprises a biodegradable polymer selected fromthe group consisting of PHA, PLA, PCL, PBS, PBSA, and PBS(c).
 38. Theshotgun shell of claim 31, wherein said biodegradable powder wadcomprises a biodegradable material selected from the group consisting ofwool felt, cork, fiber, and paperboard.
 39. The shotgun shell of claim31, wherein said biodegradable shot wad comprises a biodegradablepolymer selected from the group consisting of PHA, PLA, PCL, PBS, andPBSA.
 40. The shotgun shell of claim 31, wherein said biodegradable shotwad has a specific gravity greater than 1.1.
 41. A method of shooting ashotgun shell comprising: providing a shotgun shell having a boundarydefining a space, a biodegradable shot wad confined within said space,and a biodegradable powder wad confined within said space, wherein saidbiodegradable shot wad surrounds shot within said space, and whereinsaid biodegradable powder wad physically separates powder from said shotwithin said space; loading said shotgun shell into a shotgun having abarrel; firing said shotgun shell from said shotgun, whereby said shot,said biodegradable shot wad, and said biodegradable powder wad arelaunched out of said barrel; wherein said biodegradable shot wadcomprises a biodegradable material; wherein said biodegradable powderwad comprises a biodegradable material; wherein said biodegradablepowder wad is physically and chemically distinct from said biodegradableshot wad; and wherein upon firing of said shotgun shell from saidshotgun such that said shot exits said barrel at a velocity exceeding1,000 feet per second, said biodegradable shot wad fragments intomultiple discrete pieces within one meter of exit from said barrel; andwherein upon firing of said shotgun shell from said shotgun such thatsaid shot exits said barrel at a velocity exceeding 1,000 feet persecond, said biodegradable powder wad stays intact and does not breakapart during flight or landing.
 42. The method of claim 41, wherein saidbiodegradable shot wad comprises a biodegradable polymer selected fromthe group consisting of PHA, PLA, PCL, PBS, and PBSA.
 43. The method ofclaim 41, wherein said biodegradable powder wad comprises abiodegradable material selected from the group consisting of wool felt,cork, fiber, and paperboard.
 44. A shotgun shell comprising: abiodegradable shot wad configured to be confined within a shotgun hull;a biodegradable powder wad configured to be confined within said shotgunhull; wherein said biodegradable shot wad at least partially surroundsshot within said shotgun hull; wherein said biodegradable powder wadphysically separates powder from said shot within said shotgun hull;wherein said biodegradable shot wad comprises a biodegradable material;wherein said biodegradable powder wad comprises a biodegradablematerial; wherein upon firing of said shotgun shell, said biodegradableshot wad is configured to fragment into multiple discrete pieces duringflight or landing; and wherein upon firing of said shotgun shell, saidbiodegradable powder wad is configured to stay intact during flight andlanding; wherein said biodegradable powder wad is detached from saidbiodegradable shot wad such that said biodegradable powder wad travels adifferent distance from said shotgun during flight than all of thefragments of said biodegradable shot wad.
 45. The shotgun shell of claim44, wherein upon firing of said shotgun shell from a shotgun having abarrel such that said shot exits said barrel at a velocity exceeding1,000 feet per second, said biodegradable powder wad stays intact anddoes not break apart within one meter of exit from said barrel.
 46. Theshotgun shell of claim 44, wherein upon firing of said shotgun shellfrom a shotgun having a barrel such that said shot exits said barrel ata velocity exceeding 1,000 feet per second, said biodegradable shot wadfragments into multiple discrete pieces within one meter of exit fromsaid barrel.
 47. The shotgun shell of claim 44, wherein saidbiodegradable shot wad comprises a biodegradable polymer selected fromthe group consisting of PHA, PLA, PCL, PBS, and PBSA.
 48. The shotgunshell of claim 44, wherein said biodegradable powder wad comprises abiodegradable material selected from the group consisting of wool felt,cork, fiber, and paperboard.
 49. The shotgun shell of claim 44, whereinsaid biodegradable shot wad comprises a biodegradable polyester.
 50. Theshotgun shell of claim 44, wherein said biodegradable shot wad has aspecific gravity greater than 1.1.